Complex machines having a number of air operated tools and work feeding subassemblies are often controlled by sequentially operating a number of air cylinders. The operations of the air cylinders are programmed by sequentially operating solenoids or fluid operated valves associated with the air cylinders. The programming is usually obtained by cam units, relay circuits, electronic sequencers, or software controlled microprocessors or computers. In all of these programming systems, electrical circuits are utilized which terminate at the solenoid controlled valves associated with the air cylinders.
There are needs for simple, rugged, all mechanical devices that function to sequentially deliver pressurized fluid and non-pressurized fluid to a number of utilization devices, such as air cylinders associated with multi-unit machines. Rotary valves have been used for years in a number of industries to control the application of fluids to various machine units. In U.S. Pat. No. 4,285,365 issued Aug. 25, 1981 to G. C. Coates, et al., there is disclosed a rotary valve having a rotor with a number of axially and circumferentially spaced pockets that are sequentially presented to a series of laterally aligned exit ports. The lengths of the pockets are designed to exceed the length of the ports so that portions of the pockets may be exposed to the ports while remaining portions are exposed pressurized fluid passes through the portion of the pocket exposed to the housing, through the pocket and then through the portion of the pocket aligned with and exposed to the exit ports whereafter fluid is applied to a utilization apparatus, such as a washing machine.
Rotary air distributors are available to sequentially operate banks of air cylinders which in turn control the operation of an associated apparatus. One such air distributor is shown in U.S. Pat. No. 3,610,446 issued Oct. 5, 1971 to P. Palumbo wherein a rotor is provided with sets of veins to selectively furnish pressurized fluid to the first sides of associated fluid operated cylinders while second sets of veins on the rotor are effective to complete passage to vent second sides of the same associated fluid operated cylinders. A number of associated fluid operated cylinders are thus sequentially operated to control the operation of a series of devices, such as coke oven wharf gates.